Traprock mountain

Devil's Tower, Wyoming, a prominent basalt (traprock) landscape feature

Traprock (or basalt) mountains, ridges, (or just traps) are elevated landscape features made of the rock known as basalt and its close relatives. Basalt, an iron-rich rock otherwise known as traprock, is a characteristically dark-colored rock that weathers to shades of red and purplish-red when exposed to the air. Basalt is the substance of many elevated topographic features worldwide (hills, mountains, ridges, rock formations, etc.). Landscape features composed of basalt may include:

• Elevated sections of prehistoric ocean floor that have been raised above sea level via plate tectonics
• Prehistoric terrestrial lava floods that have become upended and/or exposed via faulting and erosion
• Various surface volcanic landforms both recent and ancient.

Because basalt has a tendency to fracture at abrupt angles, topographic features made of basalt often have a "postpile" appearance (Devil's Tower of Wyoming is a good example). Basalt ridges make up hundreds of square miles of topographic features in the northwestern United States, from Wyoming to Oregon.

Notable landforms

Prominent basalt ridges, mountains, buttes, canyons, and other landscape features include:

In the United States

• Devil's Tower in Wyoming
• The ridges and cliffs of the Columbia River Gorge in Oregon and Washington (state)
• Basalt Mountain in Colorado, for which the town of Basalt, Colorado is named.
• The Metacomet Ridge of Connecticut and Massachusetts.
• The New Jersey Palisades and Watchung Mountains
• Parts of California's inner coastal range.
• Most of the Hawaiian Islands and their mountains are composed of basalt or similar volcanic rock.

Other parts of the world

• The Paraná Traps of Brazil
• The Deccan Traps of India
• The Siberian Traps of Russia
• The Green Gardens region of Gros Morne National Park in Newfoundland
• The island of Surtsey in Iceland, a new (1963) volcanic island.

References

• Farnsworth, Elizabeth J. "Metacomet-Mattabesett Trail Natural Resource Assessment.", 2004. PDF file. Cited Nov. 20, 2007.
• Raymo, Chet and Maureen E. Written in Stone: A Geologic History of the Northeastern United States. Globe Pequot, Chester, Connecticut, 1989.
• Deccan Traps
• The Siberian Traps
• "Stratigraphy and Paleocology of the Deerfield Rift Basin (Triassic-Jurassic, Newark Supergroup), Massachusetts." Guidebook for Field Trips in the Connecticut Valley Region of Massachusetts and Adjacent States. vol. 2, 84th annual meeting, New England Intergollegiate Geological Conference, The Five Colleges. Amherst, Massachusetts. October 9-10-11, 1992: 488–535. Cited from the web, Dec. 1, 2007.
• NFS Columbia River Gorge
• NPS Devil's Tower